The Super Tuesday Outbreak

Today is the third anniversary of the Super Tuesday Tornado Outbreak. It is so called because it occurred on the date on the Super Tuesday Presidential Primaries.

Some notes…

…The outbreak was well forecast…at least one week in advance
…Caused by an unseasonably strong early season trough
…The system featured a quality warm sector with rich gulf moisture well in place well in advance
…It was outooked by the SPC as early as day 6 on 31st
…The Day 3 convective outlook called for widespread severe weather including damaging winds and tornadoes
…The probabilities were maxed out on the Day 2 outlook with a moderate risk called for…the outlook warned of long lived supercells with tornadoes
…At 12 to 18 hours out, forecaster confidence began to decrease as it appeared that the cap might hold and suppress severe storm development…there was concern that it could turn into a huge squall line and that all the hype about the tornadoes had been overblown
…There were lots of low clouds early in the morning, and it was thought that might limit the instability. Forecast soundings that morning indicated that the cap might not break.
…At 13z (7 a.m.) it was decided to upgrade to a high risk
…At noon, a special sounding from Little Rock indicated that there was more CAPE than forecast and that the cap was weaker than expected.
…By 21z (3 p.m.) the cap was nearly gone but there was still uncertainty at SPC. Was the event still being overplayed?
…Jackson had forecast a high of 73F, but they actually observed 79F

Action began just before 5 p.m. in Arkansas and some high profile action started in the Memphis area shortly after 5 p.m. Jackson, Tennessee was hard hit during the evening, and a tornadic storm affected the Nashville Metro.

Then around 1 a.m., supercells began firing over North Alabama as the low level jet increased over the state. An F4 tornado killed three people in Lawrence County. It threatened Decatur, prompting the NWS Huntsville to issue a tornado emergency for the Morgan County city. Another long track tornado killed 1 person in Jackson County, Alabama.

Category: Met 101/Weather History